Themes PIPEE NEETHWORKS SHC 321
Gravity Pipeline
consider when the water is not flowing static conditions
water will be under
pressure
and water is not flowing
so it remains constant
consider when the water is flowing in theory
velocityhead Eg
pressure head Sg
TGL HGL
P V z Pa v2 Zz
pg 2g pg 2g
consider when the water is flowing reality
rigparallel if p v2 z P v2 Zz tht the
pg 2g pg 2g
friction Darcy WeisbachEquation
heavilyinfluenced by combining the influences
length longerpipe morefriction to friti
diameter smallerdiameter morefriction lengencm
velocity fastflow morefriction 2g D v velocity mis
roughness roughpipe morefriction x frictionfactor g a81 m s
210g D D diametercm
,Secondary Losses he
something changes in thepipe Procedure for networks
friction losses occur all along the pipeline step 1 determine networklayout
at certainpoints will occur step2 determine demand requirement
expansions step3 demand patternsandpeak
contractions factors
entrances headloss m step 4 hydraulic analyses
bends
couplings he
Ivani Effigy
of s
air 2g gravitational
he changes if velocity changes acceleration mise
Basic Theory
methods
Hardy Cross loop and modalmethod
adjusts the flows or heads in onesystem equation at a time
a network consists of loops and nodes
59
flows into node
clockwise forflowand
headloss
G Eiht o
Eqi o
Loop method Hardy Cross
step i Assume valuesfor qi to satisfy Egi o
stepa calculate heifromq
steps if Enfi o then solution is correct
step4 if Enfi o then apply a correction factor to all q
and return to step 2
Cf Sq on formulasheet
zing
Nodal method
step 1 Assume values for it at eachjunction
step2 calculate q from it
step3 if Eq o then solution is correct
stepa if Eq o then apply a correctionfactor to it and return to step 2
CF SH on formula sheet
24g
, Theory from Exercises
inflow to the node is seen as positive and outflow is negative
stop with the iterations iterations are complete when Qi is zero
if no starting value is given choose a value for the first iteration
minimum allowable pressure head in the network during peak flow conditions
is 20m
other requirements that need to be met are static pressures and velocities
peak demand flow c 1.5mis
s velocities 0.6 1.2 mis
s special
fittingvelocity 6m15
min diameter 110mm for ring mains
s fire hydrants
not offmains a 75mmdiameter
Max spacing 200m
Gravity Pipeline
consider when the water is not flowing static conditions
water will be under
pressure
and water is not flowing
so it remains constant
consider when the water is flowing in theory
velocityhead Eg
pressure head Sg
TGL HGL
P V z Pa v2 Zz
pg 2g pg 2g
consider when the water is flowing reality
rigparallel if p v2 z P v2 Zz tht the
pg 2g pg 2g
friction Darcy WeisbachEquation
heavilyinfluenced by combining the influences
length longerpipe morefriction to friti
diameter smallerdiameter morefriction lengencm
velocity fastflow morefriction 2g D v velocity mis
roughness roughpipe morefriction x frictionfactor g a81 m s
210g D D diametercm
,Secondary Losses he
something changes in thepipe Procedure for networks
friction losses occur all along the pipeline step 1 determine networklayout
at certainpoints will occur step2 determine demand requirement
expansions step3 demand patternsandpeak
contractions factors
entrances headloss m step 4 hydraulic analyses
bends
couplings he
Ivani Effigy
of s
air 2g gravitational
he changes if velocity changes acceleration mise
Basic Theory
methods
Hardy Cross loop and modalmethod
adjusts the flows or heads in onesystem equation at a time
a network consists of loops and nodes
59
flows into node
clockwise forflowand
headloss
G Eiht o
Eqi o
Loop method Hardy Cross
step i Assume valuesfor qi to satisfy Egi o
stepa calculate heifromq
steps if Enfi o then solution is correct
step4 if Enfi o then apply a correction factor to all q
and return to step 2
Cf Sq on formulasheet
zing
Nodal method
step 1 Assume values for it at eachjunction
step2 calculate q from it
step3 if Eq o then solution is correct
stepa if Eq o then apply a correctionfactor to it and return to step 2
CF SH on formula sheet
24g
, Theory from Exercises
inflow to the node is seen as positive and outflow is negative
stop with the iterations iterations are complete when Qi is zero
if no starting value is given choose a value for the first iteration
minimum allowable pressure head in the network during peak flow conditions
is 20m
other requirements that need to be met are static pressures and velocities
peak demand flow c 1.5mis
s velocities 0.6 1.2 mis
s special
fittingvelocity 6m15
min diameter 110mm for ring mains
s fire hydrants
not offmains a 75mmdiameter
Max spacing 200m
